Defoamers are chemical additives widely used in pulping and paper industry, and have two main functions including defoaming and antifoaming Depending on the carrier used therein, the defoamers are classified as oil-based defoamers and water-based defoamers. The oil-based defoamer has an active ingredient emulsified or dispersed in a hydrocarbon carrier.
The oil-based defoamer emulsion is generally prepared using petroleum products, for example, organic hydrocarbons such as paraffin, diesel, mineral oil, and the like. Generally, the oil-based defoamer emulsion may undergo break-up, i.e. demulsification, during storage, and the demulsified defoamer will suffer from low effectiveness or even be ineffective; consequently, an amount of thickener is frequently required to be added in the oil-based defoamer, to increase the stability of the defoamer.
In addition, with the implementation of regulations with respect to related food and environmental safety, in the additives, including the defoamer, used in the paper industry, the content of harmful residual ingredients of organic hydrocarbons, such as aromatic hydrocarbons, is strictly limited, and thus, alternative production is carried out using mineral oils with an extremely high purity in the industry. However, the mineral oil is expensive, so inexpensive alternatives or defoamer formulations are sought to meet the requirements in terms of production and safety.
Argentina Patent Application AR056443 discloses a defoamer which has a fatty acid methyl ester (main ingredient of biodiesel) prepared from vegetable oils as a main component, and some inorganic particles, a thickener, a solvent, and other functional ingredients are also contained in the formulation. The introduction of biodiesel into the field of defoamer creates a new research subject; however, besides the contents described above, in the patent application, no contents regarding other specific components, component ratio, and preparation method of the defoamer are disclosed; the specific composition and preparation method of this defoamer cannot be acquired by those skilled in the art through the limited content disclosed in the literature.
Chinese Patent Application CN 101638871 A also disloses a new defoamer which has biodiesel introduced therein and includes a fatty acid methyl ester derivative as a component of the composition of the defoamer, in which the fatty acid methyl ester derivative is formed through an additive reaction of ethylene oxide and/or propylene oxide in the presence of a catalyst; furthermore, other active ingredients such as polyethers and natural oils are also added in the formulation of the defoamer. However, in the technical solution, the biodiesel is required to be chemically modified, which thus leads to a complex process for chemical treatment; moreover, a large amount of surfactant polyethers is contained in such defoamers, which may result in a negative influence on the sizing process during paper making.
The defoamer emulsion is typically difficult to be prepared and stored; for a successful defoamer formulation, both essential antifoaming and defoaming functions, and good product stability are required. There are various defoamer formulations in the prior art, which are mainly differentiated by the selection of the components of the defoamer, the contents of individual components, the performances of and the interaction between the components, and the preparation methods which are also of great importance.
The present inventor finds, through extensive tests and studies, a new formulation of an oil-in-water emulsion defoamer; the oil-in-water emulsion defoamer is formed using particular components and preparation method, with biodiesel as a defoaming active ingredient to completely replace the conventional organic hydrocarbons as the oil phase, so as to meet the food safety standards; the oil-in-water emulsion defoamer thus obtained has excellent stability and is not easy to break-up during storage, while having good antifoaming and defoaming performances.